Composites come in many forms and may broadly be described as the marriage or intermixing of two or more different materials in order to exploit and use the properties of each. These properties may include relatively low weight, temperature resistance, wear resistance, high strength and stiffness, including sheer, tension, compression and torsional strength, and many other properties that may be useful for a particular application.
Composite materials are formed from a variety of natural and synthetic fibres, such as fibreglass, Kevlar (trade mark), phenolic epoxy, carbon, arimid, hemp, cotton and many others, as well as resins, synthetic plastics materials of all types, rubber and many other construction materials.
Many composite materials are presently commercially available including commonly applied random fibre, reinforced, injection moulded plastics, and thermal compression moulded reinforced plastics. These commonly available materials, however, generally require expensive tooling.
In the automotive industry, for example, many automobile parts are formed of pressed and formed sheet steel structures. For example, many seat structures are formed of sheet steel pressed and/or formed to the required shape and form for structural rigidity and function. To be able to match the properties of such pressed and/or formed steel structures it is necessary to utilise advanced composites such as those employed in the aircraft, aerospace, military and motor sports industries.
While the composites industries have developed rapidly in those areas unhindered by cost competitiveness, a different situation applies in the broader manufacturing industries where a fundamental difference occurs between cost and performance. The automotive industries, however, whilst embracing composites in many areas, particularly in the high end of the market, mainstream automotive industries are substantially limited by long production cycle times, high labour and tooling costs of most high end composites as against the compromised strength and performance qualities of the lower end, less costly products.
High end advanced composites such as carbon-carbon composites, commonly used in elite motor sport and aerospace applications, require costly pre-processing of material laminates employing directional weaves and pre-impregnation of binder resins. These materials have a limited shelf life and thus impose strict cost quality management processes to ensure the final product consistency and integrity. The manufacture of composite structures using these high end materials requires labour intensive lay-up processes to achieve the desired directional orientation of the fibres and optimised strength in complex geometries. This is seen to be the most limiting and time consuming attribute of the conventional advanced composites manufacturing process. Another limiting aspect for structural parts is the requirement for costly mould tooling and large expensive autoclave ovens to cure the binder materials.
Many attempts have been made to reduce or eliminate the lay-up process of directionally controlled fibre reinforced composites. Most of these attempts have resulted in a compromise on the directionality of the fibres and hence a compromise in the performance of the product. Some of the more successful attempts have employed modular subassembly components that may be of uniform geometry and thus are more open to mass production methods. These subassembly components, however, still require extensive labour for final assembly and compromise the design flexibility with limitations on the final geometry.
Accordingly, there is a need to provide improved composite structures, and methods for their manufacture, which will facilitate the use of composites in a broad range of applications, particularly air craft manufacture, automobile manufacture and many other applications.
It is also desirable to provide composite structures that are consistently uniform.
It is also desirable to provide composite structures that require minimum labour in manufacture, assembly and production.
It is also desirable to provide composite structures which are relatively rigid and robust in use.
It is also desirable to provide composite structures which are relatively simple and economical to produce.
It is also desirable to provide composite structures that are able to be formed with the necessary structural strength, and with other properties required for their application.
It is also desirable to provide a method of forming composite structures which is able to be adapted to produce structures of a wide variety of shapes.
It is also desirable to provide methods of producing composite structures which utilise the various properties of fibres to be incorporated into the structure.